The own price elasticity at one level of aggregation can reflect both the own price and cross price elasticities at other levels of aggregation. For example, the price elasticity at the route level is a function of the own price and cross price elasticities at the price class and carrier levels of aggregation6. The interaction between these effects adds significant complexity to the analysis, requiring clarity on which own price and cross price elasticity were measured and controlled for. For example, an analysis of route-level elasticities which does not control for route substitution effects may be more appropriate for a national-level elasticity